Method and apparatus for controlling power delivered by electrosurgical probe

Electrosurgical apparatus for treating biological tissue with radiofrequency (RF) energy, the apparatus comprising:

• a radiofrequency (RF) signal generator for generating an RF waveform;
• a bipolar electrosurgical instrument arranged to deliver the RF waveform from a distal end thereof;
• a feed structure for conveying the RF waveform to the bipolar electrosurgical instrument along an RF channel;
• an RF signal detector for sampling current and voltage on the RF channel and generating therefrom a RF detection signal indicative of the current and voltage;
• and
• a controller in communication with the RF signal detector to receive the RF detection signal and to control a profile of the RF waveform,
• wherein the controller is configured to:
• set a maximum voltage limit for a voltage applied across the bipolar electrosurgical instrument;
• calculate a tissue resistance based on the RF detection signal and an impedance associated with the RF channel;
• determine an objective tissue current limit from the calculated tissue resistance and a predetermined power dissipation target;
• and
• dynamically adjust a current limit of the RF signal generator based on the determined objective tissue current limit.